The final major of the year in tennis, the US Open, has been underway for a while now. Now, the semifinals have been set after four Americans reached the quarterfinals at their home event, the most since 2002. Which players won to advance and put themselves closer to making history?

The semifinalists on the lower bracket

The first women's quarterfinals match yesterday saw American Sloane Stephens (unseeded) take on Latvian Anastasija Sevastova (16). Their match went to a third and final set that saw Stephens prevail 6-2, 3-6, 7-6, (6-4). This is the first time that Stephens has been to a semifinal in a major since the 2013 Australian Open.

It is also a big turnaround for the 24-year-old, since she missed the first two majors of the year recovering from an injury, and was then got bounced in the first round at Wimbledon. At one point she was ranked 934th in the world before her recent successes propelled her all the way up to 83rd in the world.

The ageless American Venus Williams (9) took on Czech Petra Kvitova (13) and also prevailed in a three set victory 6-3, 3-6, 7-6 (7-2). For Williams, this is her 23rd semifinal appearance in a major but her first at the US Open since 2010. This is her third semifinal appearance in a major this year, something that she has not done since 2002.

At age 37, Williams is also now the oldest women to reach the semifinals in a Grand Slam tournament since Martina Navratilova at Wimbledon in 1994.

Now Williams will face Stephens as she tries to make to her third finals appearance this year.

The semifinalists on the upper bracket

In the first women's quarterfinals match today, Czech Karolina Pliskova (1) took on American Coco Vandeweghe (20). Vandeweghe managed to pull off the upset in stunning fashion, winning in two sets 7-6 (7-4), 6-3.

With Pliskova's loss, 13 of the top 14 players in the women's bracket have lost.

Pliskova's loss also means that she will lose her ranking as number one in the world to Garbine Muguruza. This is the second time in her career Vandeweghe has reached the semifinals, as she did so earlier this year at the Australian Open where she lost to Venus Williams.

In the last quarterfinals match today, American Madison Keys (15) took on Estonian Kaia Kanepi, who is unseeded and the 418th player in the world. Keys easily defeated Kanepi 6-3, 6-3. This is the second time in her career Keys has reached the semifinals, with her first time coming in the 2015 Australian Open.

Vandeweghe and Keys will now battle it out to determine which one of them will make it to their first finals in a major. With Keys' victory, this is the first time the semifinals of the US Open has been an all American affair since 1981.